#include "unp.h"
#include "util.h"
#include "error.h"

int main(int argc, char *argv[])
{
    int i, maxi, maxfd, listenfd, connfd, sockfd;
    int nready, client[FD_SETSIZE];
    ssize_t n;
    fd_set rset, allset;
    char buf[MAXLINE];
    socklen_t clilen;
    struct sockaddr_in cliaddr, servaddr;

    listenfd = Socket(AF_INET, SOCK_STREAM, 0);

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(SERV_PORT);

    Bind(listenfd, (SA *)&servaddr, sizeof(servaddr));

    Listen(listenfd, LISTENQ);

    maxfd = listenfd;
    maxi = -1;
    for (i = 0; i < FD_SETSIZE; i++)
    {
        client[i] = -1;
    }
    FD_ZERO(&allset);
    FD_SET(listenfd, &allset);

    for (;;)
    {
        rset = allset;
        nready = select(maxfd + 1, &rset, NULL, NULL, NULL);

        if (FD_ISSET(listenfd, &rset))
        {
            clilen = sizeof(cliaddr);
            connfd = Accept(listenfd, (SA *)&cliaddr, &clilen);

            for (i = 0; i < FD_SETSIZE; i++)
            {
                if (client[i] < 0)
                {
                    client[i] = connfd;
                    break;
                }
            }
            if (i == FD_SETSIZE)
                err_quit("too many clients");

            FD_SET(connfd, &allset);
            if (connfd > maxfd)
                maxfd = connfd;
            if (i > maxi)
                maxi = i;
            if (--nready <= 0)
                continue;
        }


        for (i = 0; i < maxi; i++)
        {
            if ((sockfd = client[i]) < 0)
                continue;
            if (FD_ISSET(sockfd, &rset))
            {
                if ((n = Readn(sockfd, buf, MAXLINE)) == 0)
                {
                    // receive FIN, connection close by client
                    Close(sockfd);
                    FD_CLR(sockfd, &allset);
                    client[i] = -1;
                }
                else
                {
                    Writen(sockfd, buf, n);
                }
                if (--nready <= 0)
                    break;
            }
        }
    }
}
